Selenium-enriched fertiliser as a means to increasing milk selenium content

Take-home Message: Enriching forage and cereals with selenium by fertilisation increases milk and milk-product selenium content. 

Selenium-enriched forages and cereals significantly improved the selenium content of milk and milk products, according to scientists at Belgium’s University of Liege.

Selenium (Se) is a trace element of importance in both human and animal nutrition owing to its involvement in many processes, such as defence mechanism, antioxidant status or metabolism pathways.

The Se content in forages and in feedstuffs produced in Belgium, as is the case in many parts of Europe, is rather low. This means that Se intake of cattle could be below their requirement, resulting in in animal products with a low Se content.

“The aim of our study was to assess, on milk and milk products, the effects of dietary incorporation of roughages and cereals produced with Se enriched fertiliser,” explained Louis Istasse.

The University’s 46-cow Holstein dairy herd was divided into two groups balanced for parity number, date of calving and yield. They were offered a diet based on maize silage, grass silage, barley, dehydrated lucerne, sugar beet pulp, and soyabean meal.

In the Se group, maize, grass and barley were grown with nitrogen fertiliser enriched with Se in the form of selenate (8, 4 and 4 g selenate/ha respectively). In the control group, the fertiliser used contained no Se. The two groups of cows were milked separately with the milk being stored in two different tanks.

Samples of milk were taken at regular intervals for chemical analysis and some milk was taken to produce butter and cheese in a pilot dairy unit.

“We found that the dietary Se content was 56 and 140 μg/kg DM in the control and the Se groups respectively,” said Mr Istasse. This resulted in a significant increase (22%) in the Se content of milk from the Se group, and this carried over to the milk products. The diet high in Se also increased the fat content of the milk, but had no effect on protein and urea contents.

Full details: Dufrasne I, Robaye V, Istasse L and Hornick J-L: “Effects of dietary incorporation of roughages and barley produced with selenium-enriched fertilisers on the selenium content in milk and milk products.”

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